Correlator-based carrier sense multiple access

ABSTRACT

The disclosed subject matter is directed towards a clear channel assessment procedure based on a common preamble, such as for use with 3GPP and IEEE 802.11 technologies, or any other radio technology, including for use in the 6 GHz band. Detection of the common preamble is based on detecting known sequences in signal part, which can be detected without decoding the preamble&#39;s payload (channel) part to determine an ongoing transmission&#39;s duration. If an ongoing transmission is detected, subsequent energy detection monitoring is performed to determine when transmission ends, which can use a different energy detection threshold from what is used in the initial clear channel assessment&#39;s energy detection. The technology facilitates the usage of different sampling rates by different radio technologies that work concurrently in the same unlicensed band, by correlating a received preamble with a stored preamble that accounts for deterministic distortions arising from the different sampling rates.

RELATED APPLICATION

The subject patent application is a continuation of, and claims priorityto, U.S. patent application Ser. No. 16/459,937, filed Jul. 2, 2019, andentitled “CORRELATOR-BASED CARRIER SENSE MULTIPLE ACCESS,” the entiretyof which application is hereby incorporated by reference herein.

TECHNICAL FIELD

The subject application relates to wireless communications systems ingeneral, and more particularly to fifth generation (5G) cellularwireless communications systems and/or other next generation networks,including where base stations and mobile stations (user equipment)operate on frequencies that are shared with other base stations andmobile stations and may use different air interfaces and/or radiotechnologies.

BACKGROUND

Mobile network operators (MNOs) traditionally obtain licenses in the700-2,500 MHz range for their cellular communications systems such asthe 3rd Generation Partnership Project (3GPP) Universal MobileTelecommunications System (UMTS) or 3GPP Long-Term Evolution (LTE). Alimited amount of spectrum is unlicensed, such as the 2.4 GHzindustrial, scientific and medical (ISM) band as well as the 5 GHzUnlicensed National Information Infrastructure (U-NII) band.

License-assisted access (LAA) schemes as standardized in 3GPP LTE and3GPP New Radio (NR) allow user equipment to operate on traditionallicensed and unlicensed spectrum in a coordinated manner. Regulationsfor unlicensed spectrum exist that require user equipment and basestation devices to adhere to a set of rules, including rules that governthe coexistence among users and mobile network operators that may usethe unlicensed spectrum in an uncoordinated manner.

In the 5 GHz band, channel access procedures differ between 3GPP andIEEE 802.11 technologies, including different energy detection (ED)based thresholds, and the use of a dual threshold detection mechanismbased on energy detection followed by preamble detection (PD). Thedifferent ED thresholds and different clear channel access (CCA)procedures in the 5 GHz band results in significant issues related tothe fair and efficient shared operation of LTE LAA and 802.11.

BRIEF DESCRIPTION OF THE DRAWINGS

Non-limiting and non-exhaustive embodiments of the subject disclosureare described with reference to the following figures, wherein likereference numerals refer to like parts throughout the various viewsunless otherwise specified.

FIG. 1 illustrates an example wireless communication system includingbase stations, user equipment and a Wi-Fi network, in accordance withvarious aspects and embodiments of the subject disclosure.

FIG. 2 illustrates an example timing diagram showing communicationsbetween a base station and a mobile station device, in accordance withvarious aspects and embodiments of the subject disclosure.

FIG. 3 is an example block diagram representing clear channel assessmentdevice/logic that operates with common preamble detection, in accordancewith various aspects and embodiments of the subject disclosure.

FIG. 4 is an example block diagram representing common preambledetection on a signal part of a transmission, in accordance with variousaspects and embodiments of the subject disclosure

FIG. 5 is an example representation of monitoring via energy detectionto determine when a channel is clear for transmission of information, inaccordance with various aspects and embodiments of the subjectdisclosure

FIG. 6 is a flow diagram representing example operations of clearchannel assessment device logic, in accordance with various aspects andembodiments of the subject disclosure.

FIG. 7 illustrates example operations of a wireless network device toclear channel assessment before transmission of information, inaccordance with various aspects and embodiments of the subjectdisclosure.

FIG. 8 illustrates example operations of a wireless communicationsdevice that uses energy detection and preamble detection with respect toa common preamble to determine whether to transmit or continuemonitoring, in accordance with various aspects and embodiments of thesubject disclosure.

FIG. 9 illustrates example operations of a wireless communicationsdevice that performs subsequent energy detection on a channel when clearchannel assessment procedure determines that a channel is busy, inaccordance with various aspects and embodiments of the subjectdisclosure.

FIG. 10 illustrates an example block diagram of an example mobilehandset operable to engage in a system architecture that facilitateswireless communications according to one or more embodiments describedherein.

FIG. 11 illustrates an example block diagram of an examplecomputer/machine system operable to engage in a system architecture thatfacilitates wireless communications according to one or more embodimentsdescribed herein.

DETAILED DESCRIPTION

The technology described herein is generally directed towards a commonchannel access procedure, including where base stations and mobilestations (user equipment) operate on frequencies that are shared withother base stations and mobile stations via carrier sense multipleaccess and where base stations and mobile stations may use different airinterfaces and/or radio technologies. Aspects of the technology are moreparticularly directed to a common preamble technology for 3GPP and IEEE802.11 technologies, or any other radio technology, such as technologythat operates in the 6 GHz band. As will be understood, the commonpreamble technology relies on known sequences in the signal part of atransmission, and as a result, no protocols and/or procedures need to beimplemented to facilitate the decoding of a payload in the channel part,including a payload that may potentially be protected by forward errorcorrection (FEC) coding.

Note that different radio technologies generally may be developed andmaintained under different standards developing organizations (SDOs).Further, while the technology described herein focuses on the 6 GHzband, the technology is not limited to any particular band. For example,the technology described herein is able to provide a solution for the 5GHz band, that is, if the legacy Wi-Fi preamble is adopted with the dualED/PD mechanism described herein as an option.

One or more embodiments are now described with reference to thedrawings, wherein like reference numerals are used to refer to likeelements throughout. In the following description, for purposes ofexplanation, numerous specific details are set forth in order to providea thorough understanding of the various embodiments. It is evident,however, that the various embodiments can be practiced without thesespecific details (and without applying to any particular networkedenvironment or standard).

As used in this disclosure, in some embodiments, the terms “component,”“system” and the like are intended to refer to, or comprise, acomputer-related entity or an entity related to an operational apparatuswith one or more specific functionalities, wherein the entity can beeither hardware, a combination of hardware and software, software, orsoftware in execution. As an example, a component may be, but is notlimited to being, a process running on a processor, a processor, anobject, an executable, a thread of execution, computer-executableinstructions, a program, and/or a computer. By way of illustration andnot limitation, both an application running on a server and the servercan be a component.

One or more components may reside within a process and/or thread ofexecution and a component may be localized on one computer and/ordistributed between two or more computers. In addition, these componentscan execute from various computer readable media having various datastructures stored thereon. The components may communicate via localand/or remote processes such as in accordance with a signal having oneor more data packets (e.g., data from one component interacting withanother component in a local system, distributed system, and/or across anetwork such as the Internet with other systems via the signal). Asanother example, a component can be an apparatus with specificfunctionality provided by mechanical parts operated by electric orelectronic circuitry, which is operated by a software application orfirmware application executed by a processor, wherein the processor canbe internal or external to the apparatus and executes at least a part ofthe software or firmware application. As yet another example, acomponent can be an apparatus that provides specific functionalitythrough electronic components without mechanical parts, the electroniccomponents can comprise a processor therein to execute software orfirmware that confers at least in part the functionality of theelectronic components. While various components have been illustrated asseparate components, it will be appreciated that multiple components canbe implemented as a single component, or a single component can beimplemented as multiple components, without departing from exampleembodiments.

Further, the various embodiments can be implemented as a method,apparatus or article of manufacture using standard programming and/orengineering techniques to produce software, firmware, hardware or anycombination thereof to control a computer to implement the disclosedsubject matter. The term “article of manufacture” as used herein isintended to encompass a computer program accessible from anycomputer-readable (or machine-readable) device or computer-readable (ormachine-readable) storage/communications media. For example, computerreadable storage media can comprise, but are not limited to, magneticstorage devices (e.g., hard disk, floppy disk, magnetic strips), opticaldisks (e.g., compact disk (CD), digital versatile disk (DVD)), smartcards, and flash memory devices (e.g., card, stick, key drive). Ofcourse, those skilled in the art will recognize many modifications canbe made to this configuration without departing from the scope or spiritof the various embodiments.

Moreover, terms such as “mobile device equipment,” “mobile station,”“mobile,” subscriber station,” “access terminal,” “terminal,” “handset,”“communication device,” “mobile device” (and/or terms representingsimilar terminology) can refer to a wireless device utilized by asubscriber or mobile device of a wireless communication service toreceive or convey data, control, voice, video, sound, gaming orsubstantially any data-stream or signaling-stream. The foregoing termsare utilized interchangeably herein and with reference to the relateddrawings. Likewise, the terms “access point (AP),” “Base Station (BS),”BS transceiver, BS device, cell site, cell site device, “gNode B (gNB),”“evolved Node B (eNode B),” “home Node B (HNB)” and the like, areutilized interchangeably in the application, and refer to a wirelessnetwork component or appliance that transmits and/or receives data,control, voice, video, sound, gaming or substantially any data-stream orsignaling-stream from one or more subscriber stations. Data andsignaling streams can be packetized or frame-based flows.

Furthermore, the terms “device,” “communication device,” “mobiledevice,” “subscriber,” “customer entity,” “consumer,” “customer entity,”“entity” and the like are employed interchangeably throughout, unlesscontext warrants particular distinctions among the terms. It should beappreciated that such terms can refer to human entities or automatedcomponents supported through artificial intelligence (e.g., a capacityto make inference based on complex mathematical formalisms), which canprovide simulated vision, sound recognition and so forth.

Embodiments described herein can be exploited in substantially anywireless communication technology, comprising, but not limited to,wireless fidelity (Wi-Fi), global system for mobile communications(GSM), universal mobile telecommunications system (UMTS), worldwideinteroperability for microwave access (WiMAX), enhanced general packetradio service (enhanced GPRS), third generation partnership project(3GPP) long term evolution (LTE), third generation partnership project 2(3GPP2) ultra mobile broadband (UMB), high speed packet access (HSPA),Z-Wave, Zigbee and other 802.11 wireless technologies and/or legacytelecommunication technologies.

License-assisted access (LAA) schemes as standardized in 3GPP LTE and3GPP New Radio (NR) allow user equipment to operate on traditionallicensed and unlicensed spectrum in a coordinated manner. For example,FIG. 1 shows, in an exemplary wireless communications network 100, afirst mobile network operator that deploys base stations 120 and 121providing cellular wireless data, voice and multimedia services to userequipment in geographic areas 110 and 111, respectively. A secondoperator provides coverage to other user equipment in cell 112 by meansof base station 122. An exemplary user equipment (UE) is shown in 130.Each mobile network serves a plurality of UEs (subscribers).

Each MNO may serve UEs in respective coverage areas (“cells”) 110,111,112 via two or more frequency bands. On each frequency band, abidirectional communications link 148 is established between one or morebase station and one or more UE devices.

Further shown in FIG. 1 is a WI-FI network 172, such as operating in anunlicensed band. As is shown, a Wi-Fi device 180 communicates with theWI-FI network 172 via a bidirectional communications link 188. As inunderstood, license-assisted access allows the user equipment 130 tosimilarly have a bidirectional communications link 189 with the WI-FInetwork 172. In general, the user equipment 130 and the Wi-Fi device 180typically operate to avoid collisions, such as by physical carriersensing commonly referred to as Listen-before-Talk (LBT).

As shown in FIG. 2, a UE or mobile station device 211 performs a cellsearch procedure in an exemplary system 200 by decoding asynchronization signal 220 from a base station device 210. For instance,the base station device 210 may be one of the base stations 120, 121,122 of the wireless communications network 100 in FIG. 1 and the mobilestation device 211 may be the user equipment 130 in the wirelesscommunications network 100. The synchronization signal 220 is thentransmitted via the air interface 140 between a base station device anda mobile station device (UE).

After successfully decoding the synchronization signal 220, the mobilestation device 211 proceeds to acquiring the master system informationcarried on the physical broadcast channel (PBCH) 221. The master systeminformation configures the UE for reception of remaining systeminformation (RMSI) transmitted by a physical downlink shared channel(PDSCH) 223 which is scheduled by a physical downlink control channeltransmission (PDCCH) 221. The RMSI then configures the UE for a randomaccess procedure whereby mobile station device 211 sends a physicalrandom access channel (PRACH) 224 to base station device 210 (message1).

The base station device 210 responds via a random access response (RAR)carried by a physical downlink shared channel (PDSCH) 226 scheduled by aphysical downlink control channel transmission (PDCCH) 225 (message 2).Finally, the mobile station device 211 sends message 3 on a physicaluplink shared channel (PUSCH) 227 scheduled by message 2 in 226. Ifneeded, contention resolution is performed by the network bytransmitting message 4 from base station device 210 to the intendedmobile station device 211 informing other contending UEs of thecontention. Message 4 is scheduled by PDCCH 230 and transmitted by PDSCH231. After successful contention resolution, mobile station device 211is provided a dedicated radio resource control (RRC) configuration inPDSCH transmission 240 which is scheduled by PDCCH 241. At this point,the base station device 210 and mobile station device 211 havesuccessfully established a dedicated communication link 140.Subsequently, the mobile station device 211 may be configured accordingto the embodiments herein; the configuration is transmitted by PDSCH 251scheduled by PDCCH 250.

In a license-assisted access (LAA) system, the exemplary system 100operates on a first carrier frequency in a licensed spectrum. The PDSCH251 then configures the UE for operation on additional carriers in theunlicensed spectrum. In the first frequency band, radio resource control(RRC) and radio resource management (RRM) is under full control of thebase station devices of a given mobile network operator that holds thelicense for the first frequency band, for example, base stations 120 and121 in FIG. 1. However, the same is not true for operation on the secondfrequency band, which is shared among multiple mobile network operatorsdue to its unlicensed nature. While base stations 120 and 121 stillcontrol UEs connected to them in geographic areas 110 and 111, there maybe other base stations with other UEs that operate independently.

Alternatively, and unlike LAA operation, in a standalone (SA)deployment, the exemplary system 100 operates only on the secondfrequency band in unlicensed spectrum. Thus, a significant differencebetween a standalone system as opposed to a LAA system is that themessaging in FIG. 2 occurs on an exclusively licensed carrier in LAA,whereas for standalone the messaging takes place on the unlicensedcarrier itself. In other words, LAA systems need at least two carriers,one in the licensed spectrum and one in the unlicensed spectrum, whereasstandalone systems can be entirely deployed using only unlicensedfrequency bands. In either LAA or SA deployments, additional carriersmay be configured using the carrier aggregation (CA) framework specifiedby 3GPP for both 4G LTE and 5G NR.

Thus, unlicensed spectrum may be shared by a plurality of mobile networkoperators. In addition to base and mobile stations from mobile networkoperators, in either non-standalone (NSA) LAA or standalone (SA)deployments, additional base and mobile stations may also operate inoverlapping spectrum in unlicensed frequency bands. Examples of suchadditional base stations, represented by the WI-FI network 172 in FIG.1, are commonly referred to as access points (APs), and may comprisemanaged enterprise networks or residential access points such as Wi-Firouters, such as connected to cable set-top boxes or the like withDigital Subscriber Line (DSL), optical fiber backhaul connections, orthe like.

Several wireless communications standards exist, such as IEEE 802.11,LTE-LAA or NR based access to unlicensed spectrum (NR-U), that allowcoexistence among uncoordinated networks in unlicensed frequency bands.The technology described herein provides various enhancements to suchexisting wireless communications standards. More particularly, theembodiments described herein address problems that exist with respect toensuring that fair coexistence can be guaranteed when a plurality ofdifferent radio technologies with different air interfaces share thesame spectrum resources.

FIG. 3 depicts an example of how Clear Channel Assessment Device/Logic330 operates with respect to a transmission 332 according to the IEEE802.11ax standard. A transmission burst begins with the legacy IEEE802.11a preamble comprising the legacy short training field (L-STF),legacy long training field (L-LTF) and legacy signal (L-SIG) field. Inthis example transmission 322, the legacy preamble is followed by theIEEE 802.11ax preamble, which in turn is followed by the IEEE 802.11axdata. Note that for other members of the IEEE 802.11 family of Wi-Fistandards such as IEEE 802.11n or IEEE 802.11ac, the same procedure ofconcatenating the legacy preamble with a new preamble followed by dataapplies. To guarantee backward compatibility with the original IEEE802.11a standard, the above legacy preamble as illustrated in FIG. 3 ispart of the preambles that were introduced later as part of theevolution of the 802.11 standard.

Existing solutions are based on Carrier Sense Multiple Access (CSMA)schemes I which either physical and/or virtual carrier sensing isperformed to avoid collisions between uncoordinated nodes. For example,a base station or mobile station may perform energy detection (ED) tocheck for on-going transmissions before commencing a transmission on itsown. Energy detection is an example of physical carrier sensing and iscommonly referred to as Listen-before-Talk (LBT).

Both 3GPP LTE-LAA and NR-U as well as IEEE 802.11 use ED as part oftheir channel access procedures. For example, the 3GPP physical layerprocedures for shared spectrum channel access in 3GPP technicalspecification (TS) No. 37.213 (Version 15.2.0 from 2019-03) state: “Aslot duration T_(sl) is considered to be idle if the eNB senses thechannel during the slot duration, and the power detected by the eNB forat least 4 μS within the slot duration is less than energy detectionthreshold X_(Thresh).” Furthermore, “the eNB may transmit a transmissionincluding PDSCH/PDCCH/EPDCCH on a carrier on which LAA cell(s)transmission(s) are performed, after first sensing the channel to beidle.”

Virtual carrier sensing, on the other hand, requires decoding of thelegacy signal (L-SIG) field which carries information about the lengthof the ongoing transmission. The L-SIG has 24 bits that are transmittedover the air interface using binary phase shift keying (BPSK)modulation. The virtual carrier sensing mechanism used by IEEE 802.11relies on the devices decoding the L-SIG field in order to obtain thenetwork allocation vector (NAV). Because the preamble, specifically theL-SIG field, informs the duration of the transmission, virtual carriersensing, unlike physical energy detection, is a logical mechanism usedto determine whether the medium is busy or idle. From a power savingsperspective, the L-SIG conveys to a device the duration for which it candefer from accessing the medium. From a channel access perspective, theL-SIG lets a device set its NAV to determine for how long the sendingstation will occupy the channel. If the NAV is non-zero, the medium isconsidered busy. When then NAV expires, the medium is considered idle.

Thus, for conventional virtual carrier sensing as part of clear channelassessment (CCA), the legacy preamble indicates the duration of thetransmission in the L-SIG field. A second station detects and decodesthe preamble (i.e., PD CCA fails) and thus defers until the end of theongoing transmission. If instead CCA passes then the second station cancommence its own transmission, hence the term Carrier Sense MultipleAccess (CSMA). In theory, the same mechanism can be used if differentradio technologies share the medium.

While conventional virtual carrier sensing could work in principle, theyexhibit several drawbacks. For one, different standards for variousradio technologies, although designed for identical spectrum, mayoperate at different sampling rates. If the sampling rates arenon-integer multiples of each other, fractional sampling rate conversionneeds to be performed, which requires additional circuitry and/orsoftware at the expense of additional processing delay. For example, afirst radio standard, e.g., IEEE 802.11ax, may use a first samplingrate, whereas a second radio standard, such as 3GPP NR-U inherits itssampling rate from 3GPP NR Rel. 15 which was designed earlier andexclusively for licensed spectrum without any special consideration ofcoexistence with other radio technologies. Hence, IEEE 802.11ax and 3GPPNR-U are defined with non-identical sampling rates. A preamble for bothstandards thus would have to be defined at a single pre-determinedsampling rate, whereby at least some devices would have to convert thesampling rates to receive the preamble at a first sampling rate and thedata payload at a second sampling rate, which is undesirable.

Another drawback is that because the L-SIG field (or any other preamblecommon to different standards) needs to convey the duration of thetransmission for virtual carrier sensing, channel coding and a protocolstack is required that is common among such radio technologies usingsuch a common preamble. Generally though, channel coding and theprotocol stack are very intrinsic to each radio technology andconsequently, similar to the above issue, devices of at least some radiotechnologies would need to implement two channel coding schemes,protocol stacks and the like. For example, a first radio standard, e.g.,IEEE 802.11ax, may use a first protocol stack, channel coding scheme,and the like. A second radio standard, such as 3GPP NR-U inherits itsprotocol stack, channel coding scheme, and the like from 3GPP NR Rel. 15which was designed earlier and exclusively for licensed spectrum withoutany special consideration of coexistence with other radio technologies.Hence, IEEE 802.11ax and 3GPP NR-U are defined with non-identicalprotocol stacks, channel coding schemes, and the like. Implementing twoprotocol stacks, channel coding schemes, and the like is not desirable.

To overcome such issues, FIG. 3 illustrates performing Clear ChannelAssessment (as represented by the clear channel assessment device/logic330) that operates via physical sensing on the signal part of a commonpreamble, in contrast to also using virtual sensing on the channel part.To make this possible, both radio technologies share a common preamblecomprising the L-STF, L-LTF, and L-SIG, where the description hereinuses IEEE 802.11 terminology and procedures as examples for ease ofexposition of the underlying principles. By no means are the examplesincluding any terminology to be construed in a limiting sense. Instead,any common preamble design that is shared among two or more radiotechnologies in overlapping spectrum, that is accessed in anuncoordinated fashion by a plurality of stations, can be employed,including other aspects, features, and advantages of several embodimentsof the present disclosure as is understood. Moreover, aspects, features,or advantages of the subject matter can be exploited even if two or moreradio technologies that access a medium in an uncoordinated fashion haveseparate preambles in which only parts of the entire preamble of eachradio technology are common. For example, the preambles of differentradio standards operating in the same unlicensed bands may each comprisean identical part at the beginning, whereas after said identical part,information specific to each air interface is included in the preamble.For the embodiments, aspects, concepts, structures, functionalities orexamples described herein, such a partially common preamble is simplyreferred to as a common preamble for convenience, in a non-limiting way.Similarly, the term preamble is non-limiting and may refer to thepreamble as “channel”, “reference signal”, “signal”, “waveform” and thelike.

FIG. 4 shows the L-STF 440 and L-LTF 441 of the IEEE 802.11 legacypreamble 442. The L-STF 440 comprises ten repetitions (0-9) of a shortsymbol. A short symbol comprises 16 samples at a sampling period ofequal to 50 ns. 16*10*50 ns=8 μs. The L-LTF 441 comprises tworepetitions of a long symbol and a cyclic prefix (CP). A long symbolcomprises 64 samples whereas the CP comprises 32 samples. (64*2+32)*50ns=8 μs.

The L-STF and L-LTF fields 440 and 441, respectively, are used for timesynchronization, automatic gain control (AGC), frequency offsetcorrection, and channel estimation amongst others. These are signalsthat do not carry information. The L-SIG field (FIG. 3), on the otherhand, carries a payload, e.g., the duration of the transmission, and isthus considered a channel. Consequently, a device needs to detect theL-STF and L-LTF fields, but decode the L-SIG field (e.g., using a binaryconvolutional code in the example of IEEE 802.11 as well as coherentdemodulation of the BPSK symbols by means of channel estimation madepossible by the two L-LTF symbols).

The drawbacks above (different sampling rates, protocol stacks, channelcoding schemes, and the like) are mainly undesirable in regard tochannels which need to be decoded using forward error correction andpossibly a cyclic redundancy check (CRC). For the detection of signals,such drawbacks pertaining to different protocol stacks, channel codingschemes, and the like, do not apply because signals do not carryinformation or payloads. Further, as described herein, solutions canhandle with different sampling rates when only detection of signals isbeing considered.

Described herein, in one embodiment, is having the common preamblecomprise only a signal part, with the channel part of any preamble notused across radio technologies. A channel part may still be present, butis not common among radio technologies and only applies to specificradio technologies. For example, 3GPP NR-U and IEEE 802.11ax may share acommon preamble comprising only signals, whereas the channel part isexclusive to IEEE 802.11 devices. Similarly, 3GPP NR-U devices may usetheir own channel part such as a group common (GC) physical downlinkcontrol channel (PDCCH).

As shown in FIG. 3, the overall clear channel assessment procedure stillcomprises a dual threshold detection mechanism of energy detection (ED)334 that evaluates a received energy detection level 335 followed bycommon preamble detection (PD) 336 that evaluates a received preambledetection level 337. However, instead of ED followed by PD with virtualcarrier sense, the preamble detection only involves a signal partwhereby the clear channel assessment procedure comprising ED followed byPD uses physical carrier sensing.

More specifically, the PD device/logic 336 in the embodiments describedherein is correlator based, and does not incorporate channel decoding ordemodulation. For example, devices that use the clear channel assessmentdevice/logic 330 of FIG. 3 may use auto-correlation schemes/procedureswith a lesser computational load, and/or cross-correlation schemes witha higher computational load to detect the common preamble.Cross-correlation schemes are generally more prone to multipath fadingchannels, because the received waveform is correlated with a storedpreamble free of distortions. On the other hand, cross-correlationperforms better in noise-limited scenarios with low signal-to-noise(SNR) ratios.

Unlike virtual carrier sense, because the preamble detection stage iscorrelator based and uses the received waveform (signal) rather thandecode a payload carried by the received waveform (that is, the preambleas described herein uses the “signal” part versus the “channel” part),the duration of the ongoing transmission is unknown to other deviceseven after detecting the ongoing transmission. The ongoing transmissionthus is monitored (block 338), such as using subsequent energydetection, in one or more embodiments as described herein

More particularly, because preamble detection, even if only correlatorbased, is computationally more demanding and more power consuming thanenergy detection, in another embodiment described herein, after preambledetection successfully detects an ongoing transmission, the clearchannel assessment device/logic 330 continues to perform energydetection. Once the clear channel assessment device/logic 330 detectsthat the channel is clear, that is, the ongoing transmission 332 hasended, as shown in FIG. 5 the clear channel assessment device/logic 330can trigger communication device logic 550 to send a transmission 552.

In the example of FIG. 5, the transmission 552 is shown as including anew radio transmission NR-U part, to illustrate how a user equipmentdevice can use the physical signal part sensing to determine when anongoing 802.11 transmission has ended. In other words, FIG. 5demonstrates detecting an ongoing transmission that is using the IEEE802.11ax air interface, protocol stack and virtual carrier sensing, yetcan be performed by a 3GPP NR-U device using physical sensing on thesignal part. It is understood, however, that the technology describedherein operates with any common preamble detection that is signal based,whereby, for example, an 802.11 device can use its own instance of theclear channel assessment device/logic 330 to determine when a new radio(NR) transmission has ended.

In one or more implementations, instead of using the ED threshold hatwas used in the clear channel assessment procedure that detected thetransmission, the monitoring (block 338 of FIG. 3) of an ongoingtransmission can use a different ED threshold value, which is a functionof the energy/power received when the ongoing transmission wassuccessfully detected. A general purpose of this energy detectionprocedure with the ED threshold value that is different from the oneused for clear channel assessment is to detect the duration of theongoing transmission, without the need to process any payload in thepreamble that explicitly informs the transmission duration.

By way of example, FIG. 6 shows example operations that can be performedby clear channel assessment (CCA) device/logic 330, in which the CCAthreshold for ED and PD detection is T_(ED) and T_(PD), respectively(block 602). Note that in general 3GPP uses a single energy detection(ED) based threshold of −72 dBm, whereas Wi-Fi uses a dual thresholddetection mechanism based on energy detection at −62 dBm followed bypreamble detection (PD) at −82 dBm.

As represented by operation 604, the device/logic 330 performs ED andPD, and the levels it receives are R_(ED) and R_(PD), respectively (thenumbers are in linear scale). Operation 606 evaluates the receivedpreamble detection level R_(PD) against the received preamble detectionthreshold value T_(PD). If R_(PD)<T_(PD) then the channel is clear andthe device can transmit, as represented by operation 608.

Otherwise, the received preamble detection level R_(PD) attains thethreshold value T_(PD), R_(PD)> T_(PD) and the channel is detected asbusy. The device (e.g., a UE, such as via block 338 of FIG. 3), thenmonitors the ongoing transmission, as the device does not know the deferperiod. To this end, as represented by operation 610, the device knowsthat the background transmission level from other nodes (i.e., otherthan the node whose preamble it detected) is R_(D)=R_(ED)−R_(PD). Asrepresented by operation 610, the device sets a temporary ED thresholdto T_(ED_temp)=R_(ED). The device continues to monitor the channel byusing energy detection with T_(ED_temp). At some point, the ongoingtransmission is detected as over, and the device can transmit. Note thatas represented in FIG. 6, once the ongoing transmission is no longerdetected via the monitoring with the temporary ED threshold, the processcan return to operation 604 to perform the dual clear channel assessmentprocedure as described herein before transmitting information.

Turning to another aspect, a device can use a sampling rate that isdifferent from the one used to transmit the common preamble. Forexample, a first radio standard, e.g., IEEE 802.11ax, may use a firstsampling rate. A second radio standard, such as 3GPP NR-U, inherits itssampling rate from 3GPP NR Rel. 15 which was designed earlier andexclusively for licensed spectrum without any special consideration ofcoexistence with other radio technologies. Hence, IEEE 802.11ax and 3GPPNR-U are defined with non-identical sampling rates.

A common preamble according to aspects of the embodiments describedherein is transmitted using the first sampling rate. A 3GPP device,however, needs to receive data at the second sampling rate. Hence, onesolution is to change the sampling rate after receiving the commonpreamble at a first sampling rate to receive data payload at a secondsampling rate. Specifically, if the two sampling rates are non-integermultiples of each other, fractional sampling rate conversion needs to beperformed, which requires additional circuitry and/or software at theexpense of additional processing delay, and is thus undesirable.

Instead, according to aspects of the technology described herein, in anembodiment, the device operates at a single sampling rate, which is thesampling rate defined by its radio technology, e.g., the second samplingrate used to receive data. Because the common preamble is transmittedusing the first sampling rate, whereas the device receives it using thesecond sampling rate, (to avoid changing the sampling rate between thecommon preamble and the subsequent data transmission), the receivedsignal when the device tries to detect the common preamble is distorted.However, because the device knows the first and second sampling rate,and because the common preamble is a deterministic signal (rather than achannel with a random payload, i.e., the duration of the transmission),the parameters in such a setup are deterministic. Note that this isbeneficial a consequence of not including data/payload into a commonpreamble, which is exploited by the technology described herein.

Because the parameters are deterministic absent a channel with apayload, the aforementioned distortions are likewise deterministic.Thus, when a device tries to detect the preamble using a single samplingrate different from the one used to transmit the common preamble, thedevice can account for the aforementioned distortions. Note that this isin contrast to prior cross-correlation-based solutions that assume thatthe received waveform is correlated with a stored preamble free ofdistortions. Instead, for aspects related to embodiments describedherein, the received waveform can be correlated with a stored preamblethat accounts for the deterministic distortions that arise from usingthe second sampling rate when the common preamble is transmitted usingthe first sampling rate.

One or more aspects, such as those implemented in example operations(e.g., performed by a wireless network device comprising a processor) ofa method, are represented in FIG. 7, and are directed towards performing(operation 702) a clear channel assessment of a wireless channel todetermine whether the wireless channel is clear for use, the clearchannel assessment comprising an energy detection and a preambledetection, wherein the preamble detection comprises a correlator-basedphysical carrier sensing for a signal part comprising a known sequenceand wherein the correlator-based physical carrier sensing does notcomprise channel part decoding. Operation 704 represents, in response tothe clear channel assessment determining that the wireless channel isclear, facilitating, by the wireless network device, transmittinginformation via the wireless channel.

Aspects can comprise, in response to the clear channel assessmentdetermining that the wireless channel is not clear for use, performing,by the wireless network device, a subsequent energy detection to monitorthe wireless channel that is subsequent to the energy detection.

The energy detection can be a first energy detection using a firstenergy detection threshold value; aspects can comprise, in response tothe clear channel assessment determining that the wireless channel isnot clear for use, performing, by the wireless network device, a secondenergy detection to monitor the wireless channel comprising using asecond energy detection threshold value that is different from the firstenergy detection threshold value. Aspects can comprise determining, bythe wireless network device, the second energy detection threshold valuebased on a received energy detection level and a received preambledetection level.

The correlator-based physical carrier sensing can comprise acorrelator-based automatic correlation process. The correlator-basedphysical carrier sensing can comprise a correlator-basedcross-correlation process.

The signal part can comprise a preamble received according to a firstsampling rate that is different relative to a second sampling rate ofthe wireless device; the preamble detection can determine from thesignal part that the wireless channel is not clear for use as a resultof an ongoing transmission based on cross-correlating the preamble witha stored preamble that accounts for distortions that result from thewireless device using the second sampling rate when the preamble istransmitted using the first sampling rate.

One or more example aspects are represented in FIG. 8, and cancorrespond to a wireless communications device, comprising a processor,and a memory that stores executable instructions that, when executed bythe processor, facilitate performance of operations. Example operation802 represents obtaining a received energy detection level as part ofperforming an energy detection for a clear channel assessment. Operation804 represents obtaining a received preamble detection level as part ofperforming a preamble detection for the clear channel assessment;performing the preamble detection can comprise performingcorrelator-based physical carrier sensing for a signal part comprising aknown sequence, in which the correlator-based physical carrier sensingis independent of channel part demodulation. Operation 806 represents,in response to the clear channel assessment determining that thewireless channel is clear, transmitting via the wireless channel.Operation 808 represents, in response to the clear channel assessmentdetermining that the wireless channel is busy, performing a subsequentenergy detection to monitor the wireless channel, the subsequent energydetection being subsequent to the energy detection.

Performing the energy detection can comprise evaluating the receivedenergy detection level using a first energy detection threshold value;the subsequent energy detection can comprise monitoring the wirelesschannel using a second energy detection threshold value that isdifferent from the first energy detection threshold value.

Further operations can comprise determining the second energy detectionthreshold value based on the received energy detection level and thereceived preamble detection level. Further operations can comprisedetermining the second energy detection threshold value as the firstenergy detection threshold value minus the difference of the receivedenergy detection level minus the received preamble detection level.

The correlator-based physical carrier sensing can comprise acorrelator-based automatic correlation. The correlator-based physicalcarrier sensing can comprise a correlator-based cross-correlation.

The signal part comp can comprise a preamble transmitted with a firstsampling rate that is different than a second sampling rate of thewireless communications device; the preamble detection can determine,from the signal part, that the wireless channel is busy with an ongoingtransmission based on cross-correlating the preamble with a storedpreamble that accounts for distortions that result from the wirelesscommunications device using the second sampling rate when the preambleis transmitted using the first sampling rate.

One or more aspects, such as implemented in a machine-readable storagemedium, comprising executable instructions that, when executed by aprocessor, facilitate performance of example operations, are representedin FIG. 9. Operation 902 represents performing a clear channelassessment of a wireless channel comprising energy detection andpreamble detection, wherein the preamble detection comprisescorrelator-based physical carrier sensing for a signal part comprising aknown sequence, and wherein the preamble detection is without a virtualcarrier sense usable to determine transmission duration. Operation 904represents determining from the clear channel assessment that thewireless channel is busy with an ongoing transmission. Operation 906represents, in response to the determining that the wireless channel isbusy with the ongoing transmission, performing subsequent energydetection to detect a duration of the ongoing transmission.

The energy detection can evaluate a first received energy detectionlevel with a first energy detection threshold value, and the subsequentenergy detection can evaluate a second received second energy detectionlevel with a second energy detection threshold value that is differentfrom the first energy detection threshold value. Further operations cancomprise determining the second energy detection threshold value basedon a received energy detection level obtained for the energy detectionand a received preamble detection level obtained for the preambledetection.

The clear channel assessment can be a first clear channel assessment,and performing the subsequent energy detection can determine that thechannel is not busy; further operations can comprise, performing asecond clear channel assessment of the wireless channel, determiningfrom the second clear channel assessment that the wireless channel isnot busy, and, in response to the determining that the wireless channelis not busy, transmitting a communication via the wireless channel.

The signal part can comprise a preamble transmitted with a firstsampling rate that is different relative to a second sampling rate ofthe wireless communications device; determining from the clear channelassessment that the wireless channel is busy with the ongoingtransmission can comprise cross-correlating the preamble with a storedpreamble that accounts for distortions that result from the wirelesscommunications device using the second sampling rate when the preambleis transmitted using the first sampling rate.

The correlator-based physical carrier sensing of the preamble detectioncan comprise a correlator-based automatic correlation scheme or acorrelator-based cross-correlation scheme.

As can be seen, the technology described herein facilitates a commonchannel access procedure that, for example, can be used across aplurality of standards developing organizations that are developingseparate radio technologies that can be deployed in the same spectrum inan uncoordinated manner. The avoidance of processing payloads andforward error correction carried by a common preamble furtherfacilitates the usage of different sampling rates by different radiotechnologies that work concurrently in the same unlicensed band.

A wireless communication system can employ various cellular systems,technologies, and modulation schemes to facilitate wireless radiocommunications between devices (e.g., a UE and the network device).While example embodiments might be described for 5G new radio (NR)systems, the embodiments can be applicable to any radio accesstechnology (RAT) or multi-RAT system where the UE operates usingmultiple carriers e.g. LTE FDD/TDD, GSM/GERAN, CDMA2000 etc. Forexample, the system can operate in accordance with global system formobile communications (GSM), universal mobile telecommunications service(UMTS), long term evolution (LTE), LTE frequency division duplexing (LTEFDD, LTE time division duplexing (TDD), high speed packet access (HSPA),code division multiple access (CDMA), wideband CDMA (WCMDA), CDMA2000,time division multiple access (TDMA), frequency division multiple access(FDMA), multi-carrier code division multiple access (MC-CDMA),single-carrier code division multiple access (SC-CDMA), single-carrierFDMA (SC-FDMA), orthogonal frequency division multiplexing (OFDM),discrete Fourier transform spread OFDM (DFT-spread OFDM) single carrierFDMA (SC-FDMA), Filter bank based multi-carrier (FBMC), zero tailDFT-spread-OFDM (ZT DFT-s-OFDM), generalized frequency divisionmultiplexing (GFDM), fixed mobile convergence (FMC), universal fixedmobile convergence (UFMC), unique word OFDM (UW-OFDM), unique wordDFT-spread OFDM (UW DFT-Spread-OFDM), cyclic prefix OFDM CP-OFDM,resource-block-filtered OFDM, Wi Fi, WLAN, WiMax, and the like. However,various features and functionalities of system are particularlydescribed wherein the devices (e.g., the UEs and the network device) ofthe system are configured to communicate wireless signals using one ormore multi carrier modulation schemes, wherein data symbols can betransmitted simultaneously over multiple frequency subcarriers (e.g.,OFDM, CP-OFDM, DFT-spread OFDM, UFMC, FMBC, etc.). The embodiments areapplicable to single carrier as well as to multicarrier (MC) or carrieraggregation (CA) operation of the UE. The term carrier aggregation (CA)is also called (e.g. interchangeably called) “multi-carrier system”,“multi-cell operation”, “multi-carrier operation”, “multi-carrier”transmission and/or reception. Note that some embodiments are alsoapplicable for Multi RAB (radio bearers) on some carriers (that is dataplus speech is simultaneously scheduled).

In various embodiments, the system can be configured to provide andemploy 5G wireless networking features and functionalities. With 5Gnetworks that may use waveforms that split the bandwidth into severalsub-bands, different types of services can be accommodated in differentsub-bands with the most suitable waveform and numerology, leading toimproved spectrum utilization for 5G networks. Notwithstanding, in themmWave spectrum, the millimeter waves have shorter wavelengths relativeto other communications waves, whereby mmWave signals can experiencesevere path loss, penetration loss, and fading. However, the shorterwavelength at mmWave frequencies also allows more antennas to be packedin the same physical dimension, which allows for large-scale spatialmultiplexing and highly directional beamforming.

Performance can be improved if both the transmitter and the receiver areequipped with multiple antennas. Multi-antenna techniques cansignificantly increase the data rates and reliability of a wirelesscommunication system. The use of multiple input multiple output (MIMO)techniques, which was introduced in the third-generation partnershipproject (3GPP) and has been in use (including with LTE), is amulti-antenna technique that can improve the spectral efficiency oftransmissions, thereby significantly boosting the overall data carryingcapacity of wireless systems. The use of multiple-input multiple-output(MIMO) techniques can improve mmWave communications; MIMO can be usedfor achieving diversity gain, spatial multiplexing gain and beamforminggain.

Note that using multi-antennas does not always mean that MIMO is beingused. For example, a configuration can have two downlink antennas, andthese two antennas can be used in various ways. In addition to using theantennas in a 2×2 MIMO scheme, the two antennas can also be used in adiversity configuration rather than MIMO configuration. Even withmultiple antennas, a particular scheme might only use one of theantennas (e.g., LTE specification's transmission mode 1, which uses asingle transmission antenna and a single receive antenna). Or, only oneantenna can be used, with various different multiplexing, precodingmethods etc.

The MIMO technique uses a commonly known notation (M×N) to representMIMO configuration in terms number of transmit (M) and receive antennas(N) on one end of the transmission system. The common MIMOconfigurations used for various technologies are: (2×1), (1×2), (2×2),(4×2), (8×2) and (2×4), (4×4), (8×4). The configurations represented by(2×1) and (1×2) are special cases of MIMO known as transmit diversity(or spatial diversity) and receive diversity. In addition to transmitdiversity (or spatial diversity) and receive diversity, other techniquessuch as spatial multiplexing (comprising both open-loop andclosed-loop), beamforming, and codebook-based precoding can also be usedto address issues such as efficiency, interference, and range.

Referring now to FIG. 10, illustrated is a schematic block diagram of anexample end-user device such as a user equipment) that can be a mobiledevice 1000 capable of connecting to a network in accordance with someembodiments described herein. Although a mobile handset 1000 isillustrated herein, it will be understood that other devices can be amobile device, and that the mobile handset 1000 is merely illustrated toprovide context for the embodiments of the various embodiments describedherein. The following discussion is intended to provide a brief, generaldescription of an example of a suitable environment 1000 in which thevarious embodiments can be implemented. While the description includes ageneral context of computer-executable instructions embodied on amachine-readable storage medium, those skilled in the art will recognizethat the various embodiments also can be implemented in combination withother program modules and/or as a combination of hardware and software.

Generally, applications (e.g., program modules) can include routines,programs, components, data structures, etc., that perform particulartasks or implement particular abstract data types. Moreover, thoseskilled in the art will appreciate that the methods described herein canbe practiced with other system configurations, includingsingle-processor or multiprocessor systems, minicomputers, mainframecomputers, as well as personal computers, hand-held computing devices,microprocessor-based or programmable consumer electronics, and the like,each of which can be operatively coupled to one or more associateddevices.

A computing device can typically include a variety of machine-readablemedia. Machine-readable media can be any available media that can beaccessed by the computer and includes both volatile and non-volatilemedia, removable and non-removable media. By way of example and notlimitation, computer-readable media can comprise computer storage mediaand communication media. Computer storage media can include volatileand/or non-volatile media, removable and/or non-removable mediaimplemented in any method or technology for storage of information, suchas computer-readable instructions, data structures, program modules orother data. Computer storage media can include, but is not limited to,RAM, ROM, EEPROM, flash memory or other memory technology, CD ROM,digital video disk (DVD) or other optical disk storage, magneticcassettes, magnetic tape, magnetic disk storage or other magneticstorage devices, or any other medium which can be used to store thedesired information and which can be accessed by the computer.

Communication media typically embodies computer-readable instructions,data structures, program modules or other data in a modulated datasignal such as a carrier wave or other transport mechanism, and includesany information delivery media. The term “modulated data signal” means asignal that has one or more of its characteristics set or changed insuch a manner as to encode information in the signal. By way of example,and not limitation, communication media includes wired media such as awired network or direct-wired connection, and wireless media such asacoustic, RF, infrared and other wireless media. Combinations of the anyof the above should also be included within the scope ofcomputer-readable media.

The handset 1000 includes a processor 1002 for controlling andprocessing all onboard operations and functions. A memory 1004interfaces to the processor 1002 for storage of data and one or moreapplications 1006 (e.g., a video player software, user feedbackcomponent software, etc.). Other applications can include voicerecognition of predetermined voice commands that facilitate initiationof the user feedback signals. The applications 1006 can be stored in thememory 1004 and/or in a firmware 1008, and executed by the processor1002 from either or both the memory 1004 or/and the firmware 1008. Thefirmware 1008 can also store startup code for execution in initializingthe handset 1000. A communications component 1010 interfaces to theprocessor 1002 to facilitate wired/wireless communication with externalsystems, e.g., cellular networks, VoIP networks, and so on. Here, thecommunications component 1010 can also include a suitable cellulartransceiver 1011 (e.g., a GSM transceiver) and/or an unlicensedtransceiver 1013 (e.g., Wi-Fi, WiMax) for corresponding signalcommunications. The handset 1000 can be a device such as a cellulartelephone, a PDA with mobile communications capabilities, andmessaging-centric devices. The communications component 1010 alsofacilitates communications reception from terrestrial radio networks(e.g., broadcast), digital satellite radio networks, and Internet-basedradio services networks.

The handset 1000 includes a display 1012 for displaying text, images,video, telephony functions (e.g., a Caller ID function), setupfunctions, and for user input. For example, the display 1012 can also bereferred to as a “screen” that can accommodate the presentation ofmultimedia content (e.g., music metadata, messages, wallpaper, graphics,etc.). The display 1012 can also display videos and can facilitate thegeneration, editing and sharing of video quotes. A serial I/O interface1014 is provided in communication with the processor 1002 to facilitatewired and/or wireless serial communications (e.g., USB, and/or IEEE1394) through a hardwire connection, and other serial input devices(e.g., a keyboard, keypad, and mouse). This supports updating andtroubleshooting the handset 1000, for example. Audio capabilities areprovided with an audio I/O component 1016, which can include a speakerfor the output of audio signals related to, for example, indication thatthe user pressed the proper key or key combination to initiate the userfeedback signal. The audio I/O component 1016 also facilitates the inputof audio signals through a microphone to record data and/or telephonyvoice data, and for inputting voice signals for telephone conversations.

The handset 1000 can include a slot interface 1018 for accommodating aSIC (Subscriber Identity Component) in the form factor of a cardSubscriber Identity Module (SIM) or universal SIM 1020, and interfacingthe SIM card 1020 with the processor 1002. However, it is to beappreciated that the SIM card 1020 can be manufactured into the handset1000, and updated by downloading data and software.

The handset 1000 can process IP data traffic through the communicationcomponent 1010 to accommodate IP traffic from an IP network such as, forexample, the Internet, a corporate intranet, a home network, a personarea network, etc., through an ISP or broadband cable provider. Thus,VoIP traffic can be utilized by the handset 800 and IP-based multimediacontent can be received in either an encoded or decoded format.

A video processing component 1022 (e.g., a camera) can be provided fordecoding encoded multimedia content. The video processing component 1022can aid in facilitating the generation, editing and sharing of videoquotes. The handset 1000 also includes a power source 1024 in the formof batteries and/or an AC power subsystem, which power source 1024 caninterface to an external power system or charging equipment (not shown)by a power I/O component 1026.

The handset 1000 can also include a video component 1030 for processingvideo content received and, for recording and transmitting videocontent. For example, the video component 1030 can facilitate thegeneration, editing and sharing of video quotes. A location trackingcomponent 1032 facilitates geographically locating the handset 1000. Asdescribed hereinabove, this can occur when the user initiates thefeedback signal automatically or manually. A user input component 1034facilitates the user initiating the quality feedback signal. The userinput component 1034 can also facilitate the generation, editing andsharing of video quotes. The user input component 1034 can include suchconventional input device technologies such as a keypad, keyboard,mouse, stylus pen, and/or touch screen, for example.

Referring again to the applications 1006, a hysteresis component 1036facilitates the analysis and processing of hysteresis data, which isutilized to determine when to associate with the access point. Asoftware trigger component 1038 can be provided that facilitatestriggering of the hysteresis component 1038 when the Wi-Fi transceiver1013 detects the beacon of the access point. A SIP client 1040 enablesthe handset 1000 to support SIP protocols and register the subscriberwith the SIP registrar server. The applications 1006 can also include aclient 1042 that provides at least the capability of discovery, play andstore of multimedia content, for example, music.

The handset 1000, as indicated above related to the communicationscomponent 810, includes an indoor network radio transceiver 1013 (e.g.,Wi-Fi transceiver). This function supports the indoor radio link, suchas IEEE 802.11, for the dual-mode GSM handset 1000. The handset 1000 canaccommodate at least satellite radio services through a handset that cancombine wireless voice and digital radio chipsets into a single handhelddevice.

In order to provide additional context for various embodiments describedherein, FIG. 11 and the following discussion are intended to provide abrief, general description of a suitable computing environment 1100 inwhich the various embodiments of the embodiment described herein can beimplemented. While the embodiments have been described above in thegeneral context of computer-executable instructions that can run on oneor more computers, those skilled in the art will recognize that theembodiments can be also implemented in combination with other programmodules and/or as a combination of hardware and software.

Generally, program modules include routines, programs, components, datastructures, etc., that perform particular tasks or implement particularabstract data types. Moreover, those skilled in the art will appreciatethat the technology described herein can be practiced with othercomputer system configurations, including single-processor ormultiprocessor computer systems, minicomputers, mainframe computers,Internet of Things (IoT) devices, distributed computing systems, as wellas personal computers, hand-held computing devices, microprocessor-basedor programmable consumer electronics, and the like, each of which can beoperatively coupled to one or more associated devices.

The illustrated embodiments of the embodiments herein can be alsopracticed in distributed computing environments where certain tasks areperformed by remote processing devices that are linked through acommunications network. In a distributed computing environment, programmodules can be located in both local and remote memory storage devices.

Computing devices typically include a variety of media, which caninclude computer-readable storage media, machine-readable storage media,and/or communications media, which two terms are used herein differentlyfrom one another as follows. Computer-readable storage media ormachine-readable storage media can be any available storage media thatcan be accessed by the computer and includes both volatile andnonvolatile media, removable and non-removable media. By way of example,and not limitation, computer-readable storage media or machine-readablestorage media can be implemented in connection with any method ortechnology for storage of information such as computer-readable ormachine-readable instructions, program modules, structured data orunstructured data.

Computer-readable storage media can include, but are not limited to,random access memory (RAM), read only memory (ROM), electricallyerasable programmable read only memory (EEPROM), flash memory or othermemory technology, compact disk read only memory (CD-ROM), digitalversatile disk (DVD), Blu-ray disc (BD) or other optical disk storage,magnetic cassettes, magnetic tape, magnetic disk storage or othermagnetic storage devices, solid state drives or other solid statestorage devices, or other tangible and/or non-transitory media which canbe used to store desired information. In this regard, the terms“tangible” or “non-transitory” herein as applied to storage, memory orcomputer-readable media, are to be understood to exclude onlypropagating transitory signals per se as modifiers and do not relinquishrights to all standard storage, memory or computer-readable media thatare not only propagating transitory signals per se.

Computer-readable storage media can be accessed by one or more local orremote computing devices, e.g., via access requests, queries or otherdata retrieval protocols, for a variety of operations with respect tothe information stored by the medium.

Communications media typically embody computer-readable instructions,data structures, program modules or other structured or unstructureddata in a data signal such as a modulated data signal, e.g., a carrierwave or other transport mechanism, and includes any information deliveryor transport media. The term “modulated data signal” or signals refersto a signal that has one or more of its characteristics set or changedin such a manner as to encode information in one or more signals. By wayof example, and not limitation, communication media include wired media,such as a wired network or direct-wired connection, and wireless mediasuch as acoustic, RF, infrared and other wireless media.

With reference again to FIG. 11, the example environment 1100 forimplementing various embodiments of the aspects described hereinincludes a computer 1102, the computer 1102 including a processing unit1104, a system memory 1106 and a system bus 1108. The system bus 1108couples system components including, but not limited to, the systemmemory 1106 to the processing unit 1104. The processing unit 1104 can beany of various commercially available processors. Dual microprocessorsand other multi-processor architectures can also be employed as theprocessing unit 1104.

The system bus 1108 can be any of several types of bus structure thatcan further interconnect to a memory bus (with or without a memorycontroller), a peripheral bus, and a local bus using any of a variety ofcommercially available bus architectures. The system memory 1106includes ROM 1110 and RAM 1112. A basic input/output system (BIOS) canbe stored in a non-volatile memory such as ROM, erasable programmableread only memory (EPROM), EEPROM, which BIOS contains the basic routinesthat help to transfer information between elements within the computer1102, such as during startup. The RAM 1112 can also include a high-speedRAM such as static RAM for caching data.

The computer 1102 further includes an internal hard disk drive (HDD)1114 (e.g., EIDE, SATA), one or more external storage devices 1116(e.g., a magnetic floppy disk drive (FDD) 1116, a memory stick or flashdrive reader, a memory card reader, etc.) and an optical disk drive 1120(e.g., which can read or write from a CD-ROM disc, a DVD, a BD, etc.).While the internal HDD 1114 is illustrated as located within thecomputer 1102, the internal HDD 1114 can also be configured for externaluse in a suitable chassis (not shown). Additionally, while not shown inenvironment 1100, a solid state drive (SSD) could be used in additionto, or in place of, an HDD 1114. The HDD 1114, external storagedevice(s) 1116 and optical disk drive 1120 can be connected to thesystem bus 1108 by an HDD interface 1124, an external storage interface1126 and an optical drive interface 1128, respectively. The interface1124 for external drive implementations can include at least one or bothof Universal Serial Bus (USB) and Institute of Electrical andElectronics Engineers (IEEE) 1394 interface technologies. Other externaldrive connection technologies are within contemplation of theembodiments described herein.

The drives and their associated computer-readable storage media providenonvolatile storage of data, data structures, computer-executableinstructions, and so forth. For the computer 1102, the drives andstorage media accommodate the storage of any data in a suitable digitalformat. Although the description of computer-readable storage mediaabove refers to respective types of storage devices, it should beappreciated by those skilled in the art that other types of storagemedia which are readable by a computer, whether presently existing ordeveloped in the future, could also be used in the example operatingenvironment, and further, that any such storage media can containcomputer-executable instructions for performing the methods describedherein.

A number of program modules can be stored in the drives and RAM 1112,including an operating system 1130, one or more application programs1132, other program modules 1134 and program data 1136. All or portionsof the operating system, applications, modules, and/or data can also becached in the RAM 1112. The systems and methods described herein can beimplemented utilizing various commercially available operating systemsor combinations of operating systems.

Computer 1102 can optionally comprise emulation technologies. Forexample, a hypervisor (not shown) or other intermediary can emulate ahardware environment for operating system 1130, and the emulatedhardware can optionally be different from the hardware illustrated inFIG. 11. In such an embodiment, operating system 1130 can comprise onevirtual machine (VM) of multiple VMs hosted at computer 1102.Furthermore, operating system 1130 can provide runtime environments,such as the Java runtime environment or the .NET framework, forapplications 1132. Runtime environments are consistent executionenvironments that allow applications 1132 to run on any operating systemthat includes the runtime environment. Similarly, operating system 1130can support containers, and applications 1132 can be in the form ofcontainers, which are lightweight, standalone, executable packages ofsoftware that include, e.g., code, runtime, system tools, systemlibraries and settings for an application.

Further, computer 1102 can be enable with a security module, such as atrusted processing module (TPM). For instance with a TPM, bootcomponents hash next in time boot components, and wait for a match ofresults to secured values, before loading a next boot component. Thisprocess can take place at any layer in the code execution stack ofcomputer 1102, e.g., applied at the application execution level or atthe operating system (OS) kernel level, thereby enabling security at anylevel of code execution.

A user can enter commands and information into the computer 1102 throughone or more wired/wireless input devices, e.g., a keyboard 1138, a touchscreen 1140, and a pointing device, such as a mouse 1142. Other inputdevices (not shown) can include a microphone, an infrared (IR) remotecontrol, a radio frequency (RF) remote control, or other remote control,a joystick, a virtual reality controller and/or virtual reality headset,a game pad, a stylus pen, an image input device, e.g., camera(s), agesture sensor input device, a vision movement sensor input device, anemotion or facial detection device, a biometric input device, e.g.,fingerprint or iris scanner, or the like. These and other input devicesare often connected to the processing unit 1104 through an input deviceinterface 1144 that can be coupled to the system bus 1108, but can beconnected by other interfaces, such as a parallel port, an IEEE 1394serial port, a game port, a USB port, an IR interface, a BLUETOOTH®interface, etc.

A monitor 1146 or other type of display device can be also connected tothe system bus 1108 via an interface, such as a video adapter 1148. Inaddition to the monitor 1146, a computer typically includes otherperipheral output devices (not shown), such as speakers, printers, etc.

The computer 1102 can operate in a networked environment using logicalconnections via wired and/or wireless communications to one or moreremote computers, such as a remote computer(s) 1150. The remotecomputer(s) 1150 can be a workstation, a server computer, a router, apersonal computer, portable computer, microprocessor-based entertainmentappliance, a peer device or other common network node, and typicallyincludes many or all of the elements described relative to the computer1102, although, for purposes of brevity, only a memory/storage device1152 is illustrated. The logical connections depicted includewired/wireless connectivity to a local area network (LAN) 1154 and/orlarger networks, e.g., a wide area network (WAN) 1156. Such LAN and WANnetworking environments are commonplace in offices and companies, andfacilitate enterprise-wide computer networks, such as intranets, all ofwhich can connect to a global communications network, e.g., theInternet.

When used in a LAN networking environment, the computer 1102 can beconnected to the local network 1154 through a wired and/or wirelesscommunication network interface or adapter 1158. The adapter 1158 canfacilitate wired or wireless communication to the LAN 1154, which canalso include a wireless access point (AP) disposed thereon forcommunicating with the adapter 1158 in a wireless mode.

When used in a WAN networking environment, the computer 1102 can includea modem 1160 or can be connected to a communications server on the WAN1156 via other means for establishing communications over the WAN 1156,such as by way of the Internet. The modem 1160, which can be internal orexternal and a wired or wireless device, can be connected to the systembus 1108 via the input device interface 1144. In a networkedenvironment, program modules depicted relative to the computer 1102 orportions thereof, can be stored in the remote memory/storage device1152. It will be appreciated that the network connections shown areexample and other means of establishing a communications link betweenthe computers can be used.

When used in either a LAN or WAN networking environment, the computer1102 can access cloud storage systems or other network-based storagesystems in addition to, or in place of, external storage devices 1116 asdescribed above. Generally, a connection between the computer 1102 and acloud storage system can be established over a LAN 1154 or WAN 1156e.g., by the adapter 1158 or modem 1160, respectively. Upon connectingthe computer 1102 to an associated cloud storage system, the externalstorage interface 1126 can, with the aid of the adapter 1158 and/ormodem 1160, manage storage provided by the cloud storage system as itwould other types of external storage. For instance, the externalstorage interface 1126 can be configured to provide access to cloudstorage sources as if those sources were physically connected to thecomputer 1102.

The computer 1102 can be operable to communicate with any wirelessdevices or entities operatively disposed in wireless communication,e.g., a printer, scanner, desktop and/or portable computer, portabledata assistant, communications satellite, any piece of equipment orlocation associated with a wirelessly detectable tag (e.g., a kiosk,news stand, store shelf, etc.), and telephone. This can include WirelessFidelity (Wi-Fi) and BLUETOOTH® wireless technologies. Thus, thecommunication can be a predefined structure as with a conventionalnetwork or simply an ad hoc communication between at least two devices.

The computer is operable to communicate with any wireless devices orentities operatively disposed in wireless communication, e.g., aprinter, scanner, desktop and/or portable computer, portable dataassistant, communications satellite, any piece of equipment or locationassociated with a wirelessly detectable tag (e.g., a kiosk, news stand,restroom), and telephone. This includes at least Wi-Fi and Bluetooth™wireless technologies. Thus, the communication can be a predefinedstructure as with a conventional network or simply an ad hoccommunication between at least two devices.

Wi-Fi, or Wireless Fidelity, allows connection to the Internet from acouch at home, a bed in a hotel room, or a conference room at work,without wires. Wi-Fi is a wireless technology similar to that used in acell phone that enables such devices, e.g., computers, to send andreceive data indoors and out; anywhere within the range of a basestation. Wi-Fi networks use radio technologies called IEEE802.11 (a, b,g, n, etc.) to provide secure, reliable, fast wireless connectivity. AWi-Fi network can be used to connect computers to each other, to theInternet, and to wired networks (which use IEEE802.3 or Ethernet). Wi-Finetworks operate in the unlicensed 2.4 and 8 GHz radio bands, at an 11Mbps (802.11b) or 84 Mbps (802.11a) data rate, for example, or withproducts that contain both bands (dual band), so the networks canprovide real-world performance similar to the basic “10BaseT” wiredEthernet networks used in many offices.

As it employed in the subject specification, the term “processor” canrefer to substantially any computing processing unit or devicecomprising, but not limited to comprising, single-core processors;single-processors with software multithread execution capability;multi-core processors; multi-core processors with software multithreadexecution capability; multi-core processors with hardware multithreadtechnology; parallel platforms; and parallel platforms with distributedshared memory. Additionally, a processor can refer to an integratedcircuit, an application specific integrated circuit (ASIC), a digitalsignal processor (DSP), a field programmable gate array (FPGA), aprogrammable logic controller (PLC), a complex programmable logic device(CPLD), a discrete gate or transistor logic, discrete hardwarecomponents, or any combination thereof designed to perform the functionsdescribed herein. Processors can exploit nano-scale architectures suchas, but not limited to, molecular and quantum-dot based transistors,switches and gates, in order to optimize space usage or enhanceperformance of user equipment. A processor also can be implemented as acombination of computing processing units.

In the subject specification, terms such as “store,” “data store,” “datastorage,” “database,” “repository,” “queue”, and substantially any otherinformation storage component relevant to operation and functionality ofa component, refer to “memory components,” or entities embodied in a“memory” or components comprising the memory. It will be appreciatedthat the memory components described herein can be either volatilememory or nonvolatile memory, or can comprise both volatile andnonvolatile memory. In addition, memory components or memory elementscan be removable or stationary. Moreover, memory can be internal orexternal to a device or component, or removable or stationary. Memorycan comprise various types of media that are readable by a computer,such as hard-disc drives, zip drives, magnetic cassettes, flash memorycards or other types of memory cards, cartridges, or the like.

By way of illustration, and not limitation, nonvolatile memory cancomprise read only memory (ROM), programmable ROM (PROM), electricallyprogrammable ROM (EPROM), electrically erasable ROM (EEPROM), or flashmemory. Volatile memory can comprise random access memory (RAM), whichacts as external cache memory. By way of illustration and notlimitation, RAM is available in many forms such as synchronous RAM(SRAM), dynamic RAM (DRAM), synchronous DRAM (SDRAM), double data rateSDRAM (DDR SDRAM), enhanced SDRAM (ESDRAM), Synchlink DRAM (SLDRAM), anddirect Rambus RAM (DRRAM). Additionally, the disclosed memory componentsof systems or methods herein are intended to comprise, without beinglimited to comprising, these and any other suitable types of memory.

In particular and in regard to the various functions performed by theabove described components, devices, circuits, systems and the like, theterms (including a reference to a “means”) used to describe suchcomponents are intended to correspond, unless otherwise indicated, toany component which performs the specified function of the describedcomponent (e.g., a functional equivalent), even though not structurallyequivalent to the disclosed structure, which performs the function inthe herein illustrated example aspects of the embodiments. In thisregard, it will also be recognized that the embodiments comprise asystem as well as a computer-readable medium having computer-executableinstructions for performing the acts and/or events of the variousmethods.

Computing devices typically comprise a variety of media, which cancomprise computer-readable storage media and/or communications media,which two terms are used herein differently from one another as follows.Computer-readable storage media can be any available storage media thatcan be accessed by the computer and comprises both volatile andnonvolatile media, removable and non-removable media. By way of example,and not limitation, computer-readable storage media can be implementedin connection with any method or technology for storage of informationsuch as computer-readable instructions, program modules, structureddata, or unstructured data.

Computer-readable storage media can include, but are not limited to,random access memory (RAM), read only memory (ROM), electricallyerasable programmable read only memory (EEPROM), flash memory or othermemory technology, solid state drive (SSD) or other solid-state storagetechnology, compact disk read only memory (CD ROM), digital versatiledisk (DVD), Blu-ray disc or other optical disk storage, magneticcassettes, magnetic tape, magnetic disk storage or other magneticstorage devices or other tangible and/or non-transitory media which canbe used to store desired information.

In this regard, the terms “tangible” or “non-transitory” herein asapplied to storage, memory or computer-readable media, are to beunderstood to exclude only propagating transitory signals per se asmodifiers and do not relinquish rights to all standard storage, memoryor computer-readable media that are not only propagating transitorysignals per se. Computer-readable storage media can be accessed by oneor more local or remote computing devices, e.g., via access requests,queries or other data retrieval protocols, for a variety of operationswith respect to the information stored by the medium.

On the other hand, communications media typically embodycomputer-readable instructions, data structures, program modules orother structured or unstructured data in a data signal such as amodulated data signal, e.g., a carrier wave or other transportmechanism, and comprises any information delivery or transport media.The term “modulated data signal” or signals refers to a signal that hasone or more of its characteristics set or changed in such a manner as toencode information in one or more signals. By way of example, and notlimitation, communications media comprise wired media, such as a wirednetwork or direct-wired connection, and wireless media such as acoustic,RF, infrared and other wireless media

Further, terms like “user equipment,” “user device,” “mobile device,”“mobile,” station,” “access terminal,” “terminal,” “handset,” andsimilar terminology, generally refer to a wireless device utilized by asubscriber or user of a wireless communication network or service toreceive or convey data, control, voice, video, sound, gaming, orsubstantially any data-stream or signaling-stream. The foregoing termsare utilized interchangeably in the subject specification and relateddrawings. Likewise, the terms “access point,” “node B,” “base station,”“evolved Node B,” “cell,” “cell site,” and the like, can be utilizedinterchangeably in the subject application, and refer to a wirelessnetwork component or appliance that serves and receives data, control,voice, video, sound, gaming, or substantially any data-stream orsignaling-stream from a set of subscriber stations. Data and signalingstreams can be packetized or frame-based flows. It is noted that in thesubject specification and drawings, context or explicit distinctionprovides differentiation with respect to access points or base stationsthat serve and receive data from a mobile device in an outdoorenvironment, and access points or base stations that operate in aconfined, primarily indoor environment overlaid in an outdoor coveragearea. Data and signaling streams can be packetized or frame-based flows.

Furthermore, the terms “user,” “subscriber,” “customer,” “consumer,” andthe like are employed interchangeably throughout the subjectspecification, unless context warrants particular distinction(s) amongthe terms. It should be appreciated that such terms can refer to humanentities, associated devices, or automated components supported throughartificial intelligence (e.g., a capacity to make inference based oncomplex mathematical formalisms) which can provide simulated vision,sound recognition and so forth. In addition, the terms “wirelessnetwork” and “network” are used interchangeable in the subjectapplication, when context wherein the term is utilized warrantsdistinction for clarity purposes such distinction is made explicit.

Moreover, the word “exemplary” is used herein to mean serving as anexample, instance, or illustration. Any aspect or design describedherein as “exemplary” is not necessarily to be construed as preferred oradvantageous over other aspects or designs. Rather, use of the wordexemplary is intended to present concepts in a concrete fashion. As usedin this application, the term “or” is intended to mean an inclusive “or”rather than an exclusive “or”. That is, unless specified otherwise, orclear from context, “X employs A or B” is intended to mean any of thenatural inclusive permutations. That is, if X employs A; X employs B; orX employs both A and B, then “X employs A or B” is satisfied under anyof the foregoing instances. In addition, the articles “a” and “an” asused in this application and the appended claims should generally beconstrued to mean “one or more” unless specified otherwise or clear fromcontext to be directed to a singular form.

In addition, while a particular feature may have been disclosed withrespect to only one of several implementations, such feature may becombined with one or more other features of the other implementations asmay be desired and advantageous for any given or particular application.Furthermore, to the extent that the terms “includes” and “including” andvariants thereof are used in either the detailed description or theclaims, these terms are intended to be inclusive in a manner similar tothe term “comprising.”

The above descriptions of various embodiments of the subject disclosureand corresponding figures and what is described in the Abstract, aredescribed herein for illustrative purposes, and are not intended to beexhaustive or to limit the disclosed embodiments to the precise formsdisclosed. It is to be understood that one of ordinary skill in the artmay recognize that other embodiments having modifications, permutations,combinations, and additions can be implemented for performing the same,similar, alternative, or substitute functions of the disclosed subjectmatter, and are therefore considered within the scope of thisdisclosure. Therefore, the disclosed subject matter should not belimited to any single embodiment described herein, but rather should beconstrued in breadth and scope in accordance with the claims below.

What is claimed is:
 1. A method, comprising: performing, by a networkdevice comprising a processor, a clear channel assessment of a wirelesschannel to determine whether the wireless channel is clear for use, theclear channel assessment comprising an energy detection followed by apreamble detection, wherein the preamble detection comprises physicalcarrier sensing for a received waveform and the preamble detection isnot based on a data payload carried by the received waveform; and inresponse to the clear channel assessment determining that the wirelesschannel is clear, facilitating, by the network device, transmittinginformation via the wireless channel.
 2. The method of claim 1, whereinthe energy detection is a first energy detection, and furthercomprising, in response to the clear channel assessment determining thatthe wireless channel is not clear for use, performing, by the networkdevice, a second energy detection, to monitor the wireless channel, thatis subsequent to the first energy detection.
 3. The method of claim 2,wherein the first energy detection employs a first energy detectionthreshold as part of determining whether the wireless channel is clearfor use, and the second energy detection employs a second energydetection threshold as part of monitoring whether the wireless channelis clear for use that is different from the first energy detectionthreshold.
 4. The method of claim 3, further comprising determining, bythe network device, the second energy detection threshold based on areceived energy detection level of the received waveform and a receivedpreamble detection level of the received waveform during the clearchannel assessment.
 5. The method of claim 1, wherein the physicalcarrier sensing comprises a correlator-based automatic correlationprocess.
 6. The method of claim 1, wherein the physical carrier sensingcomprises a correlator-based cross-correlation process.
 7. The method ofclaim 1, wherein the physical carrier sensing employs a preambledetection threshold.
 8. A user equipment, comprising: a processor; and amemory that stores executable instructions that, when executed by theprocessor, facilitate performance of operations, comprising: performinga clear channel assessment of a radio channel to determine whether theradio channel is clear for use, the clear channel assessment comprisingan energy detection and a preamble detection, wherein the preambledetection comprises physical carrier sensing for a received waveform anddoes not employ a data payload carried by the received waveform; and inresponse to the clear channel assessment determining that the radiochannel is clear, transmitting signals via the radio channel.
 9. Theuser equipment of claim 8, wherein the energy detection is a firstenergy detection, and wherein the operations further comprise, inresponse to the clear channel assessment determining that the radiochannel is not clear for use, performing a second energy detection tomonitor the radio channel, wherein the second energy detection issubsequent to the first energy detection.
 10. The user equipment ofclaim 9, wherein the first energy detection employs a first energydetection threshold, and the second energy detection employs a secondenergy detection threshold that is different from the first energydetection threshold.
 11. The user equipment of claim 10, wherein theoperations further comprise determining, by the user equipment, thesecond energy detection threshold based on a received energy detectionlevel and a received preamble detection level during the clear channelassessment.
 12. The user equipment of claim 11, wherein the operationsfurther comprise determining, by the user equipment, the second energydetection threshold as the first energy detection threshold minus adifference of the received energy detection level minus the receivedpreamble detection level.
 13. The user equipment of claim 8, wherein thephysical carrier sensing comprises a correlator-based automaticcorrelation process.
 14. The user equipment of claim 8, wherein thephysical carrier sensing comprises a correlator-based cross-correlationprocess.
 15. A non-transitory machine-readable medium, comprisingexecutable instructions that, when executed by a processor of a basestation, facilitate performance of operations, comprising: determining,via a clear channel assessment, whether a wireless channel is clear foruse, the clear channel assessment comprising an energy detection and apreamble detection, wherein the preamble detection comprises physicalcarrier sensing for a received waveform that is independent of a datapayload carried by the received waveform; and in response to the clearchannel assessment determining that the wireless channel is clear,transmitting signals via the wireless channel.
 16. The non-transitorymachine-readable medium of claim 15, wherein the energy detection is afirst energy detection, and wherein the operations further comprise, inresponse to the clear channel assessment determining that the wirelesschannel is not clear for use, performing a second energy detection tomonitor the wireless channel that is subsequent to the first energydetection.
 17. The non-transitory machine-readable medium of claim 16,wherein the first energy detection applies a first function with respectto a first energy detection threshold to determine whether the wirelesschannel is clear for use, and the second energy detection applies asecond function with respect to a second energy detection threshold tomonitor whether the wireless channel is clear for use, and wherein thesecond energy detection threshold is different from the first energydetection threshold.
 18. The non-transitory machine-readable medium ofclaim 17, wherein the operations further comprise determining the secondenergy detection threshold based on a received energy detection leveland a received preamble detection level during the clear channelassessment.
 19. The non-transitory machine-readable medium of claim 18,wherein the operations further comprise determining the second energydetection threshold as the first energy detection threshold minus adifference of the received energy detection level minus the receivedpreamble detection level.
 20. The non-transitory machine-readable mediumof claim 15, wherein the physical carrier sensing comprises at least oneof a correlator-based automatic correlation process or acorrelator-based cross-correlation process.